net.sf.saxon.expr.instruct

Class LocalParam

java.lang.Object

net.sf.saxon.expr.instruct.LocalParam

All Implemented Interfaces:

SourceLocator, Binding, LocalBinding

public final class LocalParam
extends Object
implements LocalBinding, SourceLocator

The compiled form of an xsl:param element within a template in an XSLT stylesheet.

The xsl:param element in XSLT has mandatory attribute name and optional attribute select. It can also be specified as required="yes" or required="no".

This is used only for parameters to XSLT templates. For function calls, the caller of the function places supplied arguments onto the callee's stackframe and the callee does not need to do anything. Global parameters (XQuery external variables) are handled using GlobalParam.

The LocalParam class is also used to represent parameters with the saxon:iterate instruction

Field Summary

Fields

Modifier and Type	Field and Description
protected int	evaluationMode
protected int	referenceCount
protected int	slotNumber
protected StructuredQName	variableQName

Constructor Summary

Constructors

Constructor and Description
LocalParam()

Method Summary

Methods

Modifier and Type	Method and Description
void	addReference(boolean isLoopingReference) Register a variable reference that refers to the variable bound in this expression
void	checkAgainstRequiredType(ExpressionVisitor visitor) Check the select expression against the required type.
void	computeEvaluationMode()
Expression	copy() Copy an expression.
Sequence	evaluateVariable(XPathContext c) Evaluate the variable
void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
int	getCardinality() Get the cardinality of the result of this instruction.
int	getColumnNumber() Get the column number of the expression
Container	getContainer() Get the container in which this expression is located.
Expression	getConversion() Get the conversion expression
int	getConversionEvaluationMode()
int	getEvaluationMode() Get the evaluation mode of the variable
int	getInstructionNameCode() Get the name of this instruction for diagnostic and tracing purposes
IntegerValue[]	getIntegerBoundsForVariable() If the variable is bound to an integer, get the minimum and maximum possible values.
int	getLineNumber() Get the line number of the expression
int	getLocalSlotNumber() If this is a local variable held on the local stack frame, return the corresponding slot number.
int	getLocationId() Get the location ID of the expression
LocationProvider	getLocationProvider() Get the LocationProvider allowing location identifiers to be resolved.
String	getPublicId() Get the publicId of the module containing the expression (to satisfy the SourceLocator interface)
SequenceType	getRequiredType() Get the required type of this variable
Expression	getSelectExpression() Get the expression to which this variable is bound
Sequence	getSelectValue(XPathContext context) Evaluate the variable.
int	getSlotNumber() Get the slot number allocated to this variable
String	getSystemId() Get the systemId of the module containing the expression
StructuredQName	getVariableQName() Get the name of this variable
void	init(Expression select, StructuredQName qName) Initialize the properties of the variable
boolean	isAssignable() Test whether it is permitted to assign to the variable using the saxon:assign extension element.
boolean	isCompatible(LocalParam other) Check if paramater is compatible with another
boolean	isGlobal() Indicate whether the binding is local or global.
boolean	isImplicitlyRequiredParam() Ask whether this variable represents a parameter that is implicitly required, because there is no usable default value
boolean	isRequiredParam() Ask whether this variable represents a required parameter
boolean	isTunnelParam() Ask whether this variable represents a tunnel parameter
Iterator<Expression>	iterateSubExpressions() Get all the XPath expressions associated with this instruction (in XSLT terms, the expression present on attributes of the instruction, as distinct from the child instructions in a sequence construction)
Iterable<Operand>	operands() Get all the XPath expressions associated with this instruction (in XSLT terms, the expression present on attributes of the instruction, as distinct from the child instructions in a sequence construction)
void	optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType)
TailCall	processLeavingTail(XPathContext context) Process the local parameter declaration
boolean	replaceSubExpression(Expression original, Expression replacement) Replace one subexpression by a replacement subexpression
void	setContainer(Container container) Mark a variable as being in a given Container.
void	setConversion(Expression convertor) Define a conversion that is to be applied to the supplied parameter value.
void	setImplicitlyRequiredParam(boolean requiredParam) Indicate that this variable represents a parameter that is implicitly required (because there is no usable default value)
void	setLocationId(int id) Set the location ID on an expression.
void	setReferenceCount(int refCount) Set the nominal number of references to this variable
void	setRequiredParam(boolean requiredParam) Indicate that this variable represents a required parameter
void	setRequiredType(SequenceType required) Set the required type of this variable
void	setSelectExpression(Expression select) Set the expression to which this variable is bound
void	setSlotNumber(int s) Set the slot number of this variable
void	setTunnel(boolean tunnel) Indicate whether this variable represents a tunnel parameter
void	setVariableQName(StructuredQName s) Set the name of the variable
void	simplify(ExpressionVisitor visitor) Simplify this variable
void	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

variableQName

protected StructuredQName variableQName

slotNumber

protected int slotNumber

referenceCount

protected int referenceCount

evaluationMode

protected int evaluationMode

Constructor Detail

LocalParam

public LocalParam()

Method Detail

init

public void init(Expression select,
        StructuredQName qName)

Initialize the properties of the variable

Parameters:

select - the expression to which the variable is bound

qName - the name of the variable

setContainer

public void setContainer(Container container)

Mark a variable as being in a given Container. This link is used primarily for diagnostics: the container links to the location map held in the executable.

This affects the expression and all its subexpressions. Any subexpressions that are not in the same container are marked with the new container, and this proceeds recursively. However, any subexpression that is already in the correct container is not modified.

Parameters:

container - The container of this expression.

getContainer

public Container getContainer()

Get the container in which this expression is located. This will usually be a top-level construct such as a function or global variable, and XSLT template, or an XQueryExpression. In the case of free-standing XPath expressions it will be the StaticContext object

Returns:

the expression's container

setLocationId

public void setLocationId(int id)

Set the location ID on an expression.

Parameters:

id - the location id

getLocationId

public final int getLocationId()

Get the location ID of the expression

Returns:

a location identifier, which can be turned into real location information by reference to a location provider

getLineNumber

public int getLineNumber()

Get the line number of the expression

Specified by:

getLineNumber in interface SourceLocator

Returns:

the line number

getColumnNumber

public int getColumnNumber()

Get the column number of the expression

Specified by:

getColumnNumber in interface SourceLocator

Returns:

the column number

getSystemId

public String getSystemId()

Get the systemId of the module containing the expression

Specified by:

getSystemId in interface SourceLocator

getPublicId

public final String getPublicId()

Get the publicId of the module containing the expression (to satisfy the SourceLocator interface)

Specified by:

getPublicId in interface SourceLocator

getLocationProvider

public LocationProvider getLocationProvider()

Get the LocationProvider allowing location identifiers to be resolved.

Returns:

the LocationProvider used to turn the location id into real location information

setSelectExpression

public void setSelectExpression(Expression select)

Set the expression to which this variable is bound

Parameters:

select - the initializing expression

getSelectExpression

public Expression getSelectExpression()

Get the expression to which this variable is bound

Returns:

the initializing expression

setRequiredType

public void setRequiredType(SequenceType required)

Set the required type of this variable

Parameters:

required - the required type

getRequiredType

public SequenceType getRequiredType()

Get the required type of this variable

Specified by:

getRequiredType in interface Binding

Returns:

the required type

setRequiredParam

public void setRequiredParam(boolean requiredParam)

Indicate that this variable represents a required parameter

Parameters:

requiredParam - true if this is a required parameter

setImplicitlyRequiredParam

public void setImplicitlyRequiredParam(boolean requiredParam)

Indicate that this variable represents a parameter that is implicitly required (because there is no usable default value)

Parameters:

requiredParam - true if this is an implicitly required parameter

setTunnel

public void setTunnel(boolean tunnel)

Indicate whether this variable represents a tunnel parameter

Parameters:

tunnel - true if this is a tunnel parameter

setReferenceCount

public void setReferenceCount(int refCount)

Set the nominal number of references to this variable

Parameters:

refCount - the nominal number of references

getEvaluationMode

public int getEvaluationMode()

Get the evaluation mode of the variable

Returns:

the evaluation mode (a constant in ExpressionTool

getCardinality

public int getCardinality()

Get the cardinality of the result of this instruction. An xsl:variable instruction returns nothing, so the type is empty.

Returns:

the empty cardinality.

isAssignable

public boolean isAssignable()

Description copied from interface: Binding

Test whether it is permitted to assign to the variable using the saxon:assign extension element. This will only be for an XSLT global variable where the extra attribute saxon:assignable="yes" is present.

Specified by:

isAssignable in interface Binding

Returns:

true if the binding is assignable

isGlobal

public boolean isGlobal()

Description copied from interface: Binding

Indicate whether the binding is local or global. A global binding is one that has a fixed value for the life of a query or transformation; any other binding is local.

Specified by:

isGlobal in interface Binding

Returns:

true if the binding is global

getLocalSlotNumber

public int getLocalSlotNumber()

If this is a local variable held on the local stack frame, return the corresponding slot number. In other cases, return -1.

Specified by:

getLocalSlotNumber in interface LocalBinding

Returns:

the slot number on the local stack frame

isRequiredParam

public final boolean isRequiredParam()

Ask whether this variable represents a required parameter

Returns:

true if this is a required parameter

isImplicitlyRequiredParam

public final boolean isImplicitlyRequiredParam()

Ask whether this variable represents a parameter that is implicitly required, because there is no usable default value

Returns:

true if this variable is an implicitly required parameter

isTunnelParam

public final boolean isTunnelParam()

Ask whether this variable represents a tunnel parameter

Returns:

true if this is a tunnel parameter

simplify

public void simplify(ExpressionVisitor visitor)
              throws XPathException

Simplify this variable

Parameters:

visitor - an expression

Throws:

XPathException - if a failure occurs

typeCheck

public void typeCheck(ExpressionVisitor visitor,
             ContextItemStaticInfo contextItemType)
               throws XPathException

Throws:

XPathException

optimize

public void optimize(ExpressionVisitor visitor,
            ContextItemStaticInfo contextItemType)
              throws XPathException

Throws:

XPathException

computeEvaluationMode

public void computeEvaluationMode()

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Returns:

the copy of the original expression

addReference

public void addReference(boolean isLoopingReference)

Description copied from interface: Binding

Register a variable reference that refers to the variable bound in this expression

Specified by:

addReference in interface Binding

Parameters:

isLoopingReference - - true if the reference occurs within a loop, such as the predicate of a filter expression

checkAgainstRequiredType

public void checkAgainstRequiredType(ExpressionVisitor visitor)
                              throws XPathException

Check the select expression against the required type.

Parameters:

visitor - an expression visitor

Throws:

XPathException - if the check fails

getSelectValue

public Sequence getSelectValue(XPathContext context)
                        throws XPathException

Evaluate the variable. That is, get the value of the select expression if present or the content of the element otherwise, either as a tree or as a sequence

Parameters:

context - the XPath dynamic context

Returns:

the result of evaluating the variable

Throws:

XPathException - if evaluation of the select expression fails with a dynamic error

getSlotNumber

public int getSlotNumber()

Get the slot number allocated to this variable

Returns:

the slot number, that is the position allocated to the variable on its stack frame

setSlotNumber

public void setSlotNumber(int s)

Set the slot number of this variable

Parameters:

s - the slot number, that is, the position allocated to this variable on its stack frame

setVariableQName

public void setVariableQName(StructuredQName s)

Set the name of the variable

Parameters:

s - the name of the variable (a QName)

getVariableQName

public StructuredQName getVariableQName()

Get the name of this variable

Specified by:

getVariableQName in interface Binding

Returns:

the name of this variable (a QName)

setConversion

public void setConversion(Expression convertor)

Define a conversion that is to be applied to the supplied parameter value.

Parameters:

convertor - The expression to be applied. This performs type checking, and the basic conversions implied by function calling rules, for example numeric promotion, atomization, and conversion of untyped atomic values to a required type. The conversion uses the actual parameter value as input, referencing it using a VariableReference. The argument can be null to indicate that no conversion is required.

getConversion

public Expression getConversion()

Get the conversion expression

Returns:

the expression used to convert the value to the required type, or null if there is none

getConversionEvaluationMode

public int getConversionEvaluationMode()

getInstructionNameCode

public int getInstructionNameCode()

Get the name of this instruction for diagnostic and tracing purposes

Returns:

the integer name code

iterateSubExpressions

public Iterator<Expression> iterateSubExpressions()

Get all the XPath expressions associated with this instruction (in XSLT terms, the expression present on attributes of the instruction, as distinct from the child instructions in a sequence construction)

Returns:

an iterator over the subexpressions

operands

public Iterable<Operand> operands()

Get all the XPath expressions associated with this instruction (in XSLT terms, the expression present on attributes of the instruction, as distinct from the child instructions in a sequence construction)

Returns:

an iterator over the subexpressions

replaceSubExpression

public boolean replaceSubExpression(Expression original,
                           Expression replacement)

Replace one subexpression by a replacement subexpression

Parameters:

original - the original subexpression

replacement - the replacement subexpression

Returns:

true if the original subexpression is found

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws XPathException

Process the local parameter declaration

Parameters:

context - the dynamic context

Returns:

either null if processing is complete, or a tailcall if one is left outstanding

Throws:

XPathException - if a dynamic error occurs in the evaluation

getIntegerBoundsForVariable

public IntegerValue[] getIntegerBoundsForVariable()

If the variable is bound to an integer, get the minimum and maximum possible values. Return null if unknown or not applicable

Specified by:

getIntegerBoundsForVariable in interface Binding

Returns:

a pair of integers containing the minimum and maximum values for the integer value; or null if the value is not an integer or the range is unknown

evaluateVariable

public Sequence evaluateVariable(XPathContext c)

Evaluate the variable

Specified by:

evaluateVariable in interface Binding

Parameters:

c - the XPath dynamic evaluation context

Returns:

the result of evaluating the variable

isCompatible

public boolean isCompatible(LocalParam other)

Check if paramater is compatible with another

Parameters:

other - - the LocalParam object to compare

Returns:

result of the compatibility check

explain

public void explain(ExpressionPresenter out)

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Parameters:

out - the destination for output